The present invention generally relates to a frequency band allocation device and a frequency band allocation method employed in mobile communications systems in which plural frequency bands are utilized for plural communications systems.
Nowadays, the technology area for radio communication systems is developing from conventional telecommunications to a variety of schemes such as Bluetooth and radio LAN. For example, a short distance connection such as a several centimeter distance connection was done by a cable in the past, but recently radio connection technology for such short distances has been under development.
In general, radio communications systems at present, in the same area and same time, employ a single worldwide standard system, such as GSM (Global System for Mobile Communications) or IMT-2000 (International Mobile Telecommunication 2000). However, in the futures required communication systems will be diversified depending on their purposes per area and operators. In this situation, plural different systems each of which has a different purpose should be co-mingled in the same time and the same area. For that purpose, mobile stations and base stations should be compatible with these different systems.
Conventionally, a single radio device can be connected to a dedicated single network. Currently, by having several different kinds of software, a single hardware radio device can be adaptively connected to different networks. Reconfigurable radio devices are also being developed.
On the other hand, application oriented communications are required. It is tedious for users to select a radio communication route per application, and therefore a radio device is required to automatically select the optimum radio communication route for each application.
A radio communication device executing different characteristic applications is known, which can select one of plural radio communications systems for each application, based on the application's characteristics, and can determine a frequency band to be used in the selected radio communications system. Such a device is disclosed in Japanese Patent Laid-open Application No. 2004-179693.
However, most part of spectrum has already been allocated to various radio communication systems, and therefore it is difficult to obtain new spectrum for new radio communications systems.
When new and existing systems have to co-exist during a transition period in the same operator's service, it is required to establish a co-exist control system and method for smoothly transferring from the old system to the new system. In a case where different generation systems co-exist, for example, while a mobile communications system is transferred from the second generation system to the third generation system in the same frequency bands, one frequency band is shared by plural systems. In this case, it is required to establish a control system and method for allowing plural systems to co-exist. It is also required to establish a control system and method for allowing different operators such as public telecommunication operators, broadcasting operators, etc., to co-exist.
In the future, radio governmental policy regarding frequency band allocation may be changed from the license system in which operators exclusively utilize their licensed frequency bands to the registration system in which any registered operators satisfying certain standards can share and utilize certain frequency bands.
Frequency bands allocated by the registration system may be utilized by other operators, and therefore it is required to establish an efficient signal transmission system which can avoid interference from and to other systems.
It is also difficult to obtain a continuous broad bandwidth.
When a high speed transmission is required, a broad bandwidth is needed, but broad bandwidth is no longer available in spectrum which is suitable for radio communication.
Since only fragmented frequency bands are available, it is required to establish a multi-band signal transmission technology and an optimum traffic allocation method in order to utilize the fragmented frequency bands. For example, a method for separately allocating frequency bands per each use and a method for controlling resources are required to be established.
There is only one frequency band that can be utilized by one communications system. Within the same frequency band, control channels and data channels co-exist. Therefore, in order to transmit more important control information without error, it is necessary to increase a transmission power level and perform a low rate channel coding. Accordingly, frequency utilization factor degrading cannot be avoided.